This paper presents the results of a research program carried out on different trimaran hull forms and configurations suitable for medium size ferries. Resistance tests on large size scale models of the two different hull forms of main hull and outriggers, both in isolated and combined in different conditions have been carried out at the towing tank of Naples University. For each isolated hull and trimaran configuration the total resistance and running trim have been assessed. Wave pattern analysis was also performed by experimental tests and by numerical computations, so that the influence of each resistance component has been highlighted. The resulta of this work could be used as a reference in trimaran hull design and optimization.
